The term "water-based functional fluid" is used herein to refer to water-based lubricants, hydraulic fluids, cutting fluids and the like. Water-based functional fluids are not a new concept. However, in recent times, political uncertainties affecting many of world's oil supplies has made it increasingly desirable to replace oil-based functional fluids with water-based functional fluids wherever possible. Other benefits can also flow from such replacements such as decreased fire hazard and environmental pollution problems. In many cases, however, it has not been feasible to make such replacements because the water-based functional fluids could not be modified in their properties so as to perform to the same high degree as their oil-based counterparts. For example, it has been often difficult to replace certain oil-based hydraulic fluids with water-based fluids even though the desirability of doing so is evident.
Hydrocarbyl-substituted carboxylic acylating agents having at least 30 aliphatic carbon atoms in the substituent are known. The use of such carboxylic acylating agents as additives in normally liquid fuels and lubricants is discussed in U.S. Pat. Nos. 3,288,714 and 3.346,354. These acylating agents are also useful as intermediates for preparing additives for use in normally liquid fuels and lubricants as described in U.S. Pat. Nos. 2,892,786; 3,087,936; 3,163,603; 3,172,892; 3,189,544; 3,215,707; 3,219,666; 3,231,587; 3,235,503; 3,272,746; 3,306,907; 3,306,908; 3,331,776; 3,341,542; 3,346,354; 3,374,174; 3,379,515; 3,381,022; 3,413,104; 3,450,715; 3,454,607; 3,455,728; 3,476,686; 3,513,095; 3,523,768; 3,630,904; 3,632,511; 3,697,428; 3,755,169; 3,804,763; 3,836,470; 3,862,981; 3,936,480; 3,948,909; 3,950,341; 4,234,435; and 4,471,091; and French Pat. No. 2,223,415.
Nitrogen-containing, phosphorus-free carboxylic solubilizers useful in water based functional fluids are disclosed in U.S. Pat. Nos. 4,329,249; 4,368,133; 4,435,297; 4,447,348; and 4,448,703. These solubilizers are made by reacting (I) at least one carboxylic acid acylating agent having at least one hydrocarbyl substituent of from about 12 to about 500 carbon atoms with (II) at least one (a) N-(hydroxyl-substituted hydrocarbyl) amine, (b) hydroxyl-substituted poly(hydrocarbyloxy) analog of said amine (a), or (c) mixtures of (a) and (b). These patents indicate that preferred acylating agents include the substituted succinic acids or anhydrides, such as polyisobutenyl-substituted succinic anhydride, and that the amines that are useful include the primary, secondary and tertiary alkanol amines, such as diethylethanolamine and mixtures of diethylethanolamine and ethanolamine. These solubilizers are useful in dispersing or dissolving oil-soluble, water-insoluble functional additives in water-based functional fluids.
Departing now from the teachings of these prior patents, it has now been discovered that dispersants and/or solubilizers that are useful in aqueous compositions, such as aqueous concentrates, water-based functional fluids and the like, can be provided by reacting a hydrocarbyl-substituted carboxylic acid or anhydride, or ester or amide derivative of said acid or anhydride, with any amine or an alkali or alkaline earth metal or an alkali or alkaline earth metal compound under salt-forming conditions. The resulting carboxylic salts are particularly useful in dispersing and/or dissolving oil-soluble, water-insoluble functional additives in aqueous concentrates, water-based functional fluids and the like.